In heat exchangers of this type, the two tubular pipe connections serve respectively as the inlet and the outlet for a liquid, generally a mixture of glycol and water, for cooling the oil, with the latter flowing into a chamber mounted in the interior of the housing and generally consisting of a stack of pairs of half plates. Up to the present time, the two tubular pipe connections have been brazed or welded on to the corresponding apertures of the casing, which involves making a heat exchanger of such a size as to be inconvenient, especially in the case where the pipe connections are of bent configuration. In addition, fitting of the pipe connections necessitates a brazing or welding operation, and therefore requires an additional manufacturing step.